Stabilizing iridium sites via interface and reconstruction regulations for water oxidation in alkaline and acidic media

Exploring effective iridium(Ir)-based electrocatalysts with stable iridium centers is highly desirable for oxygen evolution reaction(OER).Herein,we regulated the incorporation manner of Ir in Co_(3)O_(4)support to stabilize the Ir sites for effective OER.When anchored on the surface of Co_(3)O_(4)in the form of Ir(OH)_6 species,the created Ir-OH-Co interface leads to a limited stability and poor acidic OER due to Ir leaching.When doped into Co_(3)O_(4)lattice,the analyses of X-ray absorption spectroscopy,in-situ Raman,and OER measurements show that the partially replacement of Co in Co_(3)O_(4)by Ir atoms inclines to cause strong electronic effect and activate lattice oxygen in the presence of Ir-O-Co interface,and simultaneously master the reconstruction effect to mitigate Ir dissolution,realizing the improved OER activity and stability in alkaline and acidic environments.As a result,Ir_(lat)@Co_(3)O_(4)with Ir loading of 3.67 wt%requires 294±4 mV/285±3 mV and 326±2 mV to deliver 10 mA cm^(-2)in alkaline(0.1 M KOH/1.0 M KOH)and acidic(0.5 M H_(2)SO_(4))solution,respectively,with good stability.

具有高效激子解离和明确反应位点的Tröger碱基三维多孔芳基有机骨架及其光催化近单一选择性CO_(2)转化

植物光合作用是吸收光能,把CO_(2)和水转化成富能有机物,同时释放氧气的过程.受此启发,利用太阳光将CO_(2)转化为碳氢燃料的人工碳中和技术引起了广泛关注.人工光合作用能否成功实施取决于光催化剂的设计制备.无机半导体已被广泛研究用于CO_(2)光还原反应(CO_(2)PRR),但其存在金属氧化物的带隙较宽且难以调节、导致光吸收较差和金属硫化物的光腐蚀问题严重等明显的缺点.此外,高载流子复合率和低比表面积会影响光催化效率,从而限制光子利用.因此,基于有机聚合物的无金属催化剂因其突出的可设计调控性而被提出,其中,具有超高比表面积的材料—多孔芳香骨架(PAFs)聚合物是研究热点之一,但是传统PAFs材料多为二维平面结构,用于光催化的无金属三维PAFs报道较少.此外,具有孤对电子的杂原子(N,B,F)修饰的材料可以与CO_(2)分子产生特定的偶极-四极相互作用,提高材料对CO_(2)的吸附和活化能力,是提升有机聚合物光催化剂性能的有效策略.本文采用Sonogashira-Hagihara偶联将具有不同共轭程度的芳香炔烃(2,2’,7,7‘-四乙炔基-9,9’-螺二芴,SPF-T;四(4-乙炔基苯基)甲烷,TEPM-T;1,1,2,2-四(4-乙炔基苯基)乙烯,TEPE-T)与含有N杂原子的Tröger碱聚合制备了具有三维结构的多孔芳香骨架聚合物X-TB-PAFs(X=TEPE,TEPM,SPF).通过X-射线衍射、红外光谱、13C核磁共振(NMR)以及1H NMR等表征手段验证了目标聚合物的成功合成.通过紫外-可见光谱和Mott-Schottky曲线测试研究了聚合物具体的能带结构,发现三种PAFs聚合物材料在热力学上同时满足光催化CO_(2)-CO的还原反应条件(Eθ=-0.51 Vvs.NHE,pH=7)和光催化H2O-O_(2)的氧化条件(Eθ=0.82 V vs.NHE,pH=7).V形骨架结构的Tröger碱(TB)单元和芳炔的结合赋予了聚合物刚性稳定的孔隙率以及较高的比表面积,材料中的多孔结构可以使其暴露更多的活性位点,三维框架结构为反应物接近活性位点提供了丰富的开放式空腔,这些都有利于材料对CO_(2)的捕获,增强催化剂对CO_(2)的吸附/活化能力.此外,炔基充当连接通道还可以增强体系的载流子迁移率,提升材料的光催化性能.密度泛函理论计算和光电性能测试结果表明,TB官能团引入带来的分子内极化和电子陷阱位点的优势,其与三维共轭网络结构一起协同调节了光生载流子的分离和反应位点分布.三种三维PAFs中,基于全共轭结构TEPE-T的TEPE-TB-PAF表现出最高效的光生载流子传输与分离效率,在没有助催化剂和牺牲剂的情况下表现出较好的光催化CO产率(194.50μmolg^(-1)h^(-1))和近乎单一的选择性(99.74%).全共轭TEPE-T的引入和分子内极化的存在可以促进框架内载流子的分离和迁移.材料中的电偶极矩(从负电荷到正电荷)指向TB中含有叔氮官能团的桥接位点,使其成为明确的催化反应位点.光电流和阻抗测试结果表明,TEPE-TB-PAF具有更好的电子-空穴分离能力和更小的电荷迁移位阻.三维框架构建产生的多重散射截面可以促进材料中的光子吸收,从而提高其光催化性能.理论计算和原位漫反射傅立叶变换红外光谱结果表明,材料中CO解吸的低能垒和*CHO形成的高能垒是TEPE-TB-PAF高CO产率和选择性的根本机制.综上,本文为多功能高效有机聚合物光催化剂的合成提供了有效途径,并为同时改善光催化剂的转化率和选择性提供了借鉴.

High repetition granular Co/Pt multilayers with improved perpendicular remanent magnetization for high-density magnetic recording

Thanks to the strong perpendicular magnetic anisotropy(PMA), excellent processing compatibility as well as novel spintronic phenomenon, Co/Pt multilayers have been attracting massive attention and widely used in magnetic storage.However, reversed magnetic domains come into being with the increasing layer repetition ‘N’ to reduce magneto-static energy, resulting in the remarkable diminishment of the remanent magnetization(Mr). As a result, the product of Mrand thickness(i.e., the remanent moment-thickness product, Mrt), a key parameter in magnetic recording for reliable data storing and reading, also decreases dramatically. To overcome this issue, we deposit an ultra-thick granular [Co/Pt]80multilayer with a total thickness of 68 nm on granular SiNxbuffer layer. The Mrt value, Mrto saturation magnetization(Ms) ratio as well as out of plane(OOP) coercivity(Hcoop) are high up to 2.97 memu/cm^(2), 67%, and 1940 Oe(1 Oe = 79.5775 A·m^(-1)),respectively, which is remarkably improved compared with that of continuous [Co/Pt]80multilayers. That is because large amounts of grain boundaries in the granular multilayers can efficiently impede the propagation and expansion of reversed magnetic domains, which is verified by experimental investigations and micromagnetic simulation results. The simulation results also indicate that the value of Mrt, Mr/Msratio, and Hcoopcan be further improved through optimizing the granule size, which can be experimentally realized by manipulating the process parameter of SiNxbuffer layer. This work provides an alternative solution for achieving high Mrt value in ultra-thick Co/Pt multilayers, which is of unneglectable potential in applications of high-density magnetic recording.

Distributed Active Partial Label Learning

Active learning(AL)trains a high-precision predictor model from small numbers of labeled data by iteratively annotating the most valuable data sample from an unlabeled data pool with a class label throughout the learning process.However,most current AL methods start with the premise that the labels queried at AL rounds must be free of ambiguity,which may be unrealistic in some real-world applications where only a set of candidate labels can be obtained for selected data.Besides,most of the existing AL algorithms only consider the case of centralized processing,which necessitates gathering together all the unlabeled data in one fusion center for selection.Considering that data are collected/stored at different nodes over a network in many real-world scenarios,distributed processing is chosen here.In this paper,the issue of distributed classification of partially labeled(PL)data obtained by a fully decentralized AL method is focused on,and a distributed active partial label learning(dAPLL)algorithm is proposed.Our proposed algorithm is composed of a fully decentralized sample selection strategy and a distributed partial label learning(PLL)algorithm.During the sample selection process,both the uncertainty and representativeness of the data are measured based on the global cluster centers obtained by a distributed clustering method,and the valuable samples are chosen in turn.Meanwhile,using the disambiguation-free strategy,a series of binary classification problems can be constructed,and the corresponding cost-sensitive classifiers can be cooperatively trained in a distributed manner.The experiment results conducted on several datasets demonstrate that the performance of the dAPLL algorithm is comparable to that of the corresponding centralized method and is superior to the existing active PLL(APLL)method in different parameter configurations.Besides,our proposed algorithm outperforms several current PLL methods using the random selection strategy,especially when only small amounts of data are selected to be assigned with the candidate labels.

乡村记忆档案文化创意产品的开发与利用

开发乡村记忆档案文化创意产品,有助于拓展乡村档案部门的服务方式,弥补乡村档案文化产品的缺失,有效增强乡村记忆档案的社会效益和经济效益。乡村档案部门开发和利用乡村记忆档案文化创意产品,要充分体现乡土性、真实性、合法性、创新性和实用性的特点,以跨界合作的形式,开发乡村记忆档案文化创意产品,并采用线上线下相结合的宣传和销售途径,积极做好乡村记忆档案文化创意产品的开发与利用。

阴离子交换色谱法用于肝磷脂钠的纯度评价

介绍了一种用于对肝磷脂中过硫酸化软骨素硫酸盐(OSCS)分离和定量的高效液相色谱(HPLC)方法。该方法使用阴离子交换色谱实现了肝磷脂和OSCS的完全分离,并用紫外吸收法对肝磷脂和OSCS进行了定量。实验结果表明,该方法不但具有重现性好和分析速度快(10min)的优点,而且可以在OSCS浓度低于总浓度1%时也能够对其进行有效检测。这种HPLC方法突破了毛细管电泳分析肝磷脂方法固有的局限性。

Balancing Exploration–Exploitation of Multi-verse Optimizer for Parameter Extraction on Photovoltaic Models

Extracting photovoltaic(PV)model parameters based on the measured voltage and current information is crucial in the simulation and management of PV systems.To accurately and reliably extract the unknown parameters of different PV models,this paper proposes an improved multi-verse optimizer that integrates an iterative chaos map and the Nelder–Mead simplex method,INMVO.Quantitative experiments verified that the proposed INMVO fueled by both mechanisms has more affluent populations and a more reasonable balance between exploration and exploitation.Further,to verify the feasibility and competitiveness of the proposal,this paper employed INMVO to extract the unknown parameters on single-diode,double-diode,three-diode,and PV module four well-known PV models,and the high-performance techniques are selected for comparison.In addition,the Wilcoxon signed-rank and Friedman tests were employed to test the experimental results statistically.Various evaluation metrics,such as root means square error,relative error,absolute error,and statistical test,demonstrate that the proposed INMVO works effectively and accurately to extract the unknown parameters on different PV models compared to other techniques.In addition,the capability of INMVO to stably and accurately extract unknown parameters was also verified on three commercial PV modules under different irradiance and temperatures.In conclusion,the proposal in this paper can be implemented as an advanced and reliable tool for extracting the unknown parameters of different PV models.Note that the source code of INMVO is available at https://github.com/woniuzuioupao/INMVO.

Multi-verse Optimizer with Rosenbrock and Diffusion Mechanisms for Multilevel Threshold Image Segmentation from COVID-19 Chest X-Ray Images

Coronavirus Disease 2019(COVID-19)is the most severe epidemic that is prevalent all over the world.How quickly and accurately identifying COVID-19 is of great significance to controlling the spread speed of the epidemic.Moreover,it is essential to accurately and rapidly identify COVID-19 lesions by analyzing Chest X-ray images.As we all know,image segmentation is a critical stage in image processing and analysis.To achieve better image segmentation results,this paper proposes to improve the multi-verse optimizer algorithm using the Rosenbrock method and diffusion mechanism named RDMVO.Then utilizes RDMVO to calculate the maximum Kapur’s entropy for multilevel threshold image segmentation.This image segmentation scheme is called RDMVO-MIS.We ran two sets of experiments to test the performance of RDMVO and RDMVO-MIS.First,RDMVO was compared with other excellent peers on IEEE CEC2017 to test the performance of RDMVO on benchmark functions.Second,the image segmentation experiment was carried out using RDMVO-MIS,and some meta-heuristic algorithms were selected as comparisons.The test image dataset includes Berkeley images and COVID-19 Chest X-ray images.The experimental results verify that RDMVO is highly competitive in benchmark functions and image segmentation experiments compared with other meta-heuristic algorithms.

内嵌碳点的无铅金属卤化物单晶用于单组分白光发射体

白光发光二极管(WLED)照明光源的发展对于降低能源消耗具有重要意义.然而,常用的基于荧光粉转换技术的WLED器件存在自吸收严重、显色指数低和稀土元素供应风险等多方面的不足.对此,本文通过组装蓝光碳点(CDs)和无铅黄光金属卤化物(Cs_(2)InCl_(5)·H_(2)O:Sb^(3+)),开发了一种新的单组分白光发射材料.采用液-液扩散辅助结晶方法,本工作成功地将CDs嵌入到Cs_(2)InCl_(5)·H_(2)O:Sb^(3+)晶体中,复合材料呈现出白光发射.调节CDs和Cs_(2)InCl_(5)·H_(2)O:Sb^(3+)的比例可实现冷/暖色调可调.使用这种“内嵌CDs的卤化物晶体”复合材料作为转换器,我们成功制造出单一体系WLED,其显色指数(CRI)高达93.6,为下一代室内高品质WLED照明光源提供了一种便捷有效的策略.

Finite-time coordinated path-following control of leader-following multi-agent systems

This paper presents applications of the continuous feedback method to achieve path-following and a formation moving along the desired orbits within a finite time.It is assumed that the topology for the virtual leader and followers is directed.An additional condition of the so-called barrier function is designed to make all agents move within a limited area.A novel continuous finite-time path-following control law is first designed based on the barrier function and backstepping.Then a novel continuous finite-time formation algorithm is designed by regarding the path-following errors as disturbances.The settling-time properties of the resulting system are studied in detail and simulations are presented to validate the proposed strategies.

Hemodialysis bilayer bionic blood vessels developed by the mechanical stimulation of hepatitis B viral X(HBX)genetransfected hepatic stellate cells

Artificial vascular graft(AVG)fistula is widely used for hemodialysis treatment in patients with renal failure.However,it has poor elasticity and compliance,leading to stenosis and thrombosis.The ideal artificial blood vessel for dialysis should replicate the structure and components of a real artery,which is primarily maintained by collagen in the extracellular matrix(ECM)of arterial cells.Studies have revealed that in hepatitis B virus(HBV)-induced liver fibrosis,hepatic stellate cells(HSCs)become hyperactive and produce excessive ECM fibers.Furthermore,mechanical stimulation can encourage ECM secretion and remodeling of a fiber structure.Based on the above factors,we transfected HSCs with the hepatitis B viral X(HBX)gene for simulating the process of HBV infection.Subsequently,these HBX-HSCs were implanted into a polycaprolactonepolyurethane(PCL-PU)bilayer scaffold in which the inner layer is dense and the outer layer consists of pores,which was mechanically stimulated to promote the secretion of collagen nanofiber from the HBX-HSCs and to facilitate crosslinking with the scaffold.We obtained an ECM-PCL-PU composite bionic blood vessel that could act as access for dialysis after decellularization.Then,the vessel scaffold was implanted into a rabbit’s neck arteriovenous fistula model.It exhibited strong tensile strength and smooth blood flow and formed autologous blood vessels in the rabbit’s body.Our study demonstrates the use of human cells to create biomimetic dialysis blood vessels,providing a novel approach for creating clinical vascular access for dialysis.